Combined mountings for expulsion fuses and surge gaps



Sept. 23, 1947. L. A. PHILLIPS [2,427,743

COMBINED MOUNTINGS FOR EXPULSION FUSES AND SURGE GAPS Filed April 10, l943 2 Sheets-Sheet 1 BY 6mm ATTORNEY P 1947 L. A. PHILLIPS 2,427,743

COMBINED MOUNTINGS FOR EXPULSION FUSES AND SURGE GAPS Filed April 10,1943 2 Sheets-Sheet 2' ATTORNEY.

Patented Sept. 23, 1947 COMBINED MOUNTINGS FOR EXPULSION FUSES AND SURGEGAPS Leon A. Phillips, Hazleton, Pa., assignor to Line Material Company,Milwaukee, Wis., a corporation of Delaware Application April 10, 1943,Serial No. 482,569

3 Claims. 1

This invention relates to protective equipment for electric powersystems and has to do more especially with the fusing and lightningprotection of rural distribution lines.

It usually is the policy of public utility companies concerningdistribution lines which are expected to carry relatively large payloads, particularly where service interruptions must be kept at aminimum, to use the best obtainable materials throughout, includingfuses and lightning arresters of the most dependable character. But inconstructing rural lines where the anticipated load is small and theprobable gross income per mile of line proportionately low, it often isnot possible to employ the highest grade protective equipment and stillbe able to amortize the investment out of earnings and maintain rateswhich are low enough to induce a major portion of the prospectivecustomers to utilize the service.

On the other hand, rural service is mainly of a domestic character, withrespect to which periodic outages are not altogether intolerable; andthe average farmer is willing to put up with occasionable blackouts inorder to obtain electric service at a price which is comfortably withinhis reach.

As a part of the effort to provide reasonably satisfactory servicenotwithstanding inadequate operating income, there has heretofore beenwidely used an inexpensive, unhoused, nondropout expulsion fuse designedto be suspended directly from a line wire and capable of being quicklyand easily installed. Such equipment is operative, but it is not goodpractice to use line wires as supporting media.

In addition to fusing the lines against overloads .and short circuits,the transformers must be protected against lightning and other heavysurge discharges; and the desirable Way to accomplish that end is toprovide lightning arresters of the kind which function dependably toprevent power current flowing to ground following each surgedischarge-which flow to ground inherently gives rise to more or lesswidespread outages through the operation of sub-station circuit breakersor the blowing of feeder line main fuses. Lightning protection, per se,can be achieved through the use of a simple spark-gap connected betweenline and ground, but such an expedient provides only for diversion ofthe high voltage surges and usually results in line outages due to powercurrent being short-circuited to ground whenever lightning strikes. Insome lo- 2 calities that means lines out of commission almost every timethere is a lightning storm.

The present invention has for its object to provide means which, at theleast possible cost, will render it feasible to provide better fusingand adequate lightning protection for rural lines; and to that end theinvention consist-s, in part, in providing an arrester of the expulsiongap type of inexpensive design, and a mounting for the same which willalso accommodate an expulsion type line fuse of the kind previouslymentioned which was originally designed to be suspended on a line wire.My new mounting is designed for attachment either directly to a pole oralternatively to .a cross-arm, and in either case includes an open gapin series with the expulsion gap device. A feature of the invention,both as respects the fuse and the expulsion gap is that both thosedevices can easily be attached and removed, and there are ampleclearances to enable servicemen to operate without inconvenience and toassure against short-circuiting, while at the same time the wholeinstallation is not overlarge and the cost is such that its use iseconomically possible on a large percentage of rural lines.

In order fully to appreciate the significance of the present invention,it must be realized that what .is sought is improved rural service atthe least posssible added cost; and it must be taken into considerationthat over-all operating cost includes not only depreciation and intereston original investment, but also cost of service maintenance. Outagesspell both man-hours, which have to be paid for, and loss of revenueduring service interruptions, and when those factors are weighed it isfound that the present invention is a contribution to rural lineeconomy-even with out evaluating the good will which is a reflection ofimproved service.

The devices of the present invention are characterized by simplicity andlow cost, yet without sacrifice of essential structural strength andrigidity; and they are further distinguished by ready adaptability forattachment to poles and cross-arms and accessibility for servicing.

Two embodiments of the invention are depicted in the accompanyingdrawings, wherein:

Fig. 1 is a front elevational View of .a rural line fuse and gapmounting in conformity with this invention;

Fig. 2 is an endwise elevational view of the structure of Fig. 1;

Fig. 3 is an enlarged view of the upper end of a fuse or expulsion gapFig. 4 is an endwise elevational view of an alternative form of theinvention; and

Fig. 5 is a front elevational view of the structure of Fig. 4.

In Figs. 1 and 2 reference numeral I identifies a fragment of a powerline pole to which the fuse and expulsion gap mounting is shownattached. The mounting, as a whole, is identified by reference numeral2, While the fuse is designated by numeral 3 and the expulsion gap bynumeral 4. The device is ordinarily used in conjunction with adistribution transformer and is supported on the same pole. The functionof the fuse is, of course, to protect the line and transformer againstthe injurious effects of overloads and short circuitswhich it does byinterrupting the line circuit; and the primary function of the expulsiongap is to provide an easy path to ground for lightning and other highvoltage surges, thus diverting the high potential currents away from thetransformer windings.

Fuse 3 is of a type which was designed originally to be hung directly ona feeder line wire at a junction point where a branch line is connectedto the feederthere being a distribution transformer at said junction, tothe primary side of which the fuse is connected in series. The fusecomprises an expulsion tube 5 which may be of horn fiber or of someother insulating material, such as Bakelite, lined with fiber or othergasevolving material. To the upper end of the expulsion tube (see Fig.3) is secured a metal ferrule 6 from which projects laterally adownwardly extending hook 'I, to the lower end of which is riveted anupwardly extending leaf spring 8. From the opposite side of the ferrulethere projects a loop 9 which is designed for engagement with a hotstick; and to the upper end of the ferrule is detachably secured a capIE), which is threaded to the ferrule and removable to permit afuse-link to be inserted in the cartridge. Ferrule 6 and cap IO,conjointly, constitute terminal means for grippingly engaging the upperend of the fuse-link and establishing electrical contact therewith. Thebore of tube 5 is open at its lower end and is closed at its upper endby cap I0.

Attached to the lower end of tube 5 is a metal collar I I designed toreceive a conventional splitbolt connector I2, and having an integrallaterally projecting arm I3 which terminates in a flip-out mechanism I4designed to operate, when the fuse blows, to withdraw from the openlower end of the tube a flexible conductive leader I5 which forms thelower terminal of the fuse-link. The flip-out mechanism is described inReissue Patent No. 22,149 to William O. Schultz. The fuselink is ofconventional design and includes a fusible section situated within theupper portion of the bore of tube 5 and normally kept under tension bythe action of the flip-out mechanism on leader I5. The split-boltconnector I2 is electrically connected through collar II, arm I3 andmechanism I4 to the leader I5, and is designed for attachment to oneprimary terminal of a branch line transformer.

Expulsion gap 4 is identical externally at its upper end with the upperend of the fusesee Fig. 3. Here the parts corresponding to fuse partsB-I I) inclusive are numbered Iii-26 inclusive. Tube 2| may be of hornfiber or of other insulating materials, such as Bakelite, lined withhorn fiber or other gas-evolving material. The bore is open at its lowerend. Inside tube 2] and extending downwardly from ferrule I6 and cap 20,to

Which it is connected, is a rod (not shown) Which functions as a sparkelectrode. This rod extends only part way down the bore of tube 2I, andthe remainder of the bore constitutes an enclosed constricted passagewaywhich forms at least the major portion of the spark-gapall of which isin keeping with well known practice. To the lower end of tube 2| issecured a metal ferrule 22 which serves as the lower spark electrode;and integral with said ferrule is a laterally projecting arm 23 which isadapted to receive a split-bolt connector 24. The latter is intended forconnection to a ground wire 25.

The mode of operation and purpose of expulsion gap devices are familiarto those who are employed in the construction and maintenance of powerdistribution systems. But for the information of those who may not beversed in this art, it seems worthwhile to state that the function ofthe device is to provide a medium through which lightning discharges andother high voltage surges can find an easy path from the line conductorto ground, but which will not provide a path over which power currentcan flow to ground. An ordinary spark-gap, without any arc-extinguishingmeans will function to permit discharge of lightning to ground, and sucha gap would meet all requirements were it not for the fact thationization thereof b the high voltage discharge transforms the gap intoa conductive space path for power current, which will continue to flowafter the initial surge has subsided and until a fuse or circuitbreaker, operating as a consequence of such flow, opens the linecircuit, as well as the ground circuit, and thus causes a lineoutagewhich spells interruption of service until the fault is cleared.In order to forestall such outages it is necessary to extinguish quicklyor prevent the formation of a power circuit are in the spark-gap; andthat is the function which is achieved in an expulsion gap device overand above and in addition to the function of a simple gap. Extinction ofthe are which forms between the spaced electrodes of device 4 is broughtabout b the fact that the fiber bore surface of tube 2I has theproperty, when subjected to the high temperature of an arc, of evolvingarc-extinguishing vapor or gas which de-ionizes the arc path. If thepower current is of substantial magnitude, gas is evolved in such volumeand expanded so rapidly within the bore of the tube that the dischargethereof from the open lower end of the tube takes place with explosiveviolence. The explosion sweeps out of the tube bore all or most of theionized particles which would serve to maintain a conductive path, andwhen, thereafter, the alternating power current has reached and passedthe succeeding zero point of its cycle and is again increasing inmagnitude, there no longer obtains the space ionization which is acondition precedent to ability of the applied power voltage tore-establish the arc.

Mounting 2 includes a Z-shape strap 26, the upper vertical 16g of whichis shown secured to pole I by means of lag-screws or bolts 21. The lowervertical leg of strap 26 is attached, by means of machine screws 28, toone end of a porcelain or glass insulator 29 which serves to insulateall live parts from the pole. Insulator 29 has a metal insert 3!! at oneend, having tapped holes to accommodate screws 28, and has a secondmetal insert 3I at the opposite end which is tapped to accommodate anadditional pair of machine screws 32, 32. The two metal inserts 30, 3Iare not electrically connected.

An angle iron 33 is attached at its mid-portion,

by means of screws 32., to insert 3| and depending from one end thereofis a metal stirrup 34 which is secured to the angle iron by means of twobolts 35 35. Interposed between angle iron 33 and stirrup 34 is theupstanding leg 36a of a guideplate 36 having a hornizontal leg 36b.Stirrup 34. is formed with an integral horizontal bar 340. which isproportioned for engagement with the bight of hook 1, as clearly shownin Fig. ,2. As will be apparent, fuse 3 is hooked onto stirrup 34 andfirmly secured thereto by the pressure exerted by spring 8. Thehorizontal leg 36b of guide-plate 36 overlies the upper end of the fuseand serves as a guide when inserting the fuse in the stirrup. Theutility of such a guide will be more evident when it is considered thatthe fuse usually is mounted by means of a long hot-stick engaging loop9.

Stirrup 34 has an integral lug 34b which is apertured to receive asplit-bolt connector 31 by means of which connection is made to thefeeder line. The upper terminal of the fuse-link is thus connected toline through the medium of ferrule 6 and stirrup 34. The other terminalof the fuselink is connected to the branch line-usually a transformerprimary terminal-through the me dium of split-bolt connector I2.

Also connecteed to angle iron 33 and depending therefrom is a secondinsuiator 38, having a metal insert 39 at its upper end which is tappedto receive a pair of machine screws 40, 40 by means of which theinsulator is secured to the angle iron. The lower end of insulator 38has a metal insert 4!, to which is attached by machine screws 42 adepending metal stirrup 43, which is similar to stirrup 34 except thatit is not provided with a split-bolt connector and is provided with arightangular base portion at its upper end having apertures for screws42. Also attached to insert 4 I, by means of screws 42, is a plate 44and a metal strip 45 which functions both as a spark-gap electrode andas a guide for aiding the lineman when at-- taching the expulsion gapdevice by means of a hot-stick. The purpose of plate 44 is to preventexpulsion gap 4 being attached to stirrup 43 at the wrong side thereof.Since the lower terminal of the expulsion gap is grounded it isnecessary to maintain adequate spacing between it and the lower terminalof the fuse, and if the gap device were turned around that spacing wouldbe decreased.

The upper end of spark electrode 45 is spaced to form a gap at 46 withone end of angle iron 33, the latter being tapered, as shown, to form asparking point. It will be observed that gap 46 is in series withexpulsion gap 4 and forms a part of the path to ground. Gap 46 servesnormally to isolate the expulsion gap from the line and therebyprecludes the possibility of power current leaking to ground throughtube 2| of the expulsion gap device.

It will be seen that the above-described mounting comprises only simpleinsulators-which are not costlytogether with other parts which are easyto make and assemble, and entails the use of a minimum of material. Thenew mounting permits of the use of a type of expulsion fuse which isstandard equipment and comparatively inexpensive, while at the same timebeing adapted to receive an expulsion gap which is similarlyinexpensive.

The alternative structure of Figs. 4 and differs in form but not infunction or mode of operation from the structure of Figs. 1 and 2.Either Structure can be attached to a cross-arm or directly to a pole.As illustrated, the structure of Figs. 1 and 2 is attached directly to apole whereas the structure of Figs. 4 and 5 is adapted more particularlyfor attachment to a cross-arm.

But these are not distinctions which substantially differentiate the twoembodiments.

In Figs. 4 and 5 the fuse and expulsion gap devices are identical withthose of Figs. 1 and 2 and they are identified by reference numerals 3and 4, respectively. All component parts of the fuse and expulsion gapdevices of Figs. 4 and 5 bear primed reference numerals in conformitywith their counterparts in Figs. 1 and 2.

The mounting includes a vertical channel iron 47 apertured toaccommodate a pair of bolts 48, 48' which are spaced apart sufficientlyto embrace between them a cross-arm, not shown. A piece of strap iron 49drilled to match the bolt holes in channel 4! is designed to bearagainst the cross-arm oppositely to said channel and provide ananchorage for the bolts. Piece 49 operates conjointly with channel 41and bolts 48 to secure the mounting to the cross-arm. An advantageintrinsic in this type of mounting is that no bolt holes need be boredin the cross-arm and the structure can be moved along the cross-arm,after loosening nuts 55, for the purpose of adjusting or changing itsposition.

Secured to the lower end of channel 47, by means of machine screws 5!,is an insulator 52 having a metal insert 53 which is drilled and tappedto receive screws 5!. Clamped between the web of channel 41 and the baseof insert 53 is a bent metal strip 54 which constitutes one of a pair ofgap electrodes defining a spark gap 55 in shunt to insulator 52. Thecompanion gap electrode is a metal strip identified by reference numeral56.

The other end of insulator 52 has a metal insert 5'! to which is securedby machine screws 58, 59 a second Vertical channel iron 60, bent offset,as shown, to conserve space and carrying at its upper end a secondinsulator 6|, attached thereto by a pair of machine screws 62, 62, whichalso serve to secure to the channel iron the metal strip 56.

The outer end of insulator 6! has a metal insert 63 which is drilled andtapped to receive a pair of machine screws 64, 64 by which are securedto insert 63 a brass double-stirrup casting 65 and a, sheet metal hoodor guide-plate 66, having the same function as guide-plate 36 of Figs. 1and 2. Casting 65 is skeletonized as shown and includes two horizontalbar portions 65a and 655 on which are hung, respectively, expulsion gapdevice 2| and expulsion fuse 5. It will be observed that casting 65performs the same functions as the two stirrups 34 and 43 of Figs. 1 and2, and it is for that reason that I herein refer to casting 65 as adouble stirrup casting. Said casting has oppositely projecting ears 65cand 65d, each of which is pierced as shown at 65d to form two segmentalopenings divided by a narrow bridge of metal 65c, which is proportionedto fit the slot of a split-bolt connector 66. The latter can be securedto either of the two ears 550 or Wei-whichever happens to be the moreconvenient. Connector 66 is connected to a line wire by means ofconductor 61.

t will be seen that the upper terminals of both the fuse and theexpulsion gap device are normally at line potential. In the embodimentof Figs. 1. and 2. only the fuse has its upper terminal normally at linepotential, the expulsion gap being isolated from the line by reason ofgap 46.

The lower connector I2 of fuse 5' is usually connected to a transformerprimary terminal by means of a conductor 68, and the lower terminalconnector 24' of expulsion gap device 2| is connected via conductor 69to a split-bolt connector 10 which is carried by an angle clip I l--thelatter being attached to channel iron 60 by means of screw 58.

It will be observed that the lower electrode 22' of expulsion gap device2| is connected to ground via conductor 69, connector 10, clip H,channel iron 60, gap electrode 56, gap 55, gap electrode 54, channeliron 41, split-bolt connector 12 and ground wire 13; and it will be seenthat gap 55 is on the ground side of the expulsion gap device whereas inthe structure of Figs. 1 and 2 gap 45 is on the line side of expulsiongap device 4.

A feature which has been incorporated in the structure of Figs. 4 and 5is a cross-bar 14. This is secured at its middle to channel iron 60 bymeans of screw 58 and is bent at Ma and Mb to embrace the two flanges ofchannel iron 60 in such manner as to prevent rotation of the crossbararound screw 58. The cross-bar has two oppositely projecting arms whichare notched respectively at 14c and 14d, which portions are designed toengage the hooks, respectively, of the expulsion gap device and thefuse, when these are removed by a lineman from their normal positions oncastin 65 and hung on the crossbar. By virtue of cross-bar 14 it isunnecessary for the lineman to leave the expulsion gap device and fusedangling on conductors B9 and 98 while he is working on the pole.

What is claimed is:

1. Electrical protective equipment comprising an expulsion fuse and anexpulsion gap device, said fuse and said device each being mountable anddemountable independently of the other and provided at its upper endwith a terminal having an attachment hook whereby it is adapted to besuspended from a support and to make electrical connection to saidsupport, said hooks being characterized in that they render said fuseand said device quickly attachable and detachable to and from their saidsupport, and unitary mounting means for said fuse and said device, saidmounting means including a member adapted for attachment to a pole, aninsulator secured at one end to said member and projecting therefrom, asecond member secured to the other end of said insulator and carriedthereby, a second insulator secured at one end to said second memher andcarried by said second member, a pair of stirrup-like supporting meansfor said fuse and said device, at least one of said supporting meansbeing carried by said second insulator, said fuse and said device beingheld in spaced relation by said supporting means, said mounting meansalso including an open gap connected in series with said expulsion gapdevice.

2. Electrical protective equipment comprising an expulsion fuse and anexpulsion gap device, said fuse and said device each being mountable anddemountable independently of the other and provided at its upper endwith a terminal having an attachment hook, and unitary mountingstructure for said fuse and said device, said mounting structureincluding a bracket member adapted for attachment to a pole, aninsulator secured at one end to said bracket member and projectingtherefrom, an elongated conductive member secured at its mid-portion tothe other end of said insulator and extending horizontally in oppositedirections therefrom, a conductive stirrup secured to and depending fromone end portion of said conductive member, said stirrup having ahorizontal bar portion at its lower end which is adapted to receive thehook of said fusc terminal, said stirrup serving as a support for saidfuse, a second insulator secured to and depending from the other endportion of said conductive member remotely from said stirrup, a secondstirrup secured to and depending from the lower end of said secondinsulator and having a horizontal bar portion at its lower end forreceiving the hook of said expulsion gap device terminal, said secondstirrup serving as a support for said expulsion gap device, and aspark-electrode secured at one end to the lower end of said secondinsulator and forming a spark gap with said conductive member.

3. Electrical protective equipment comprising an expulsion fuse and anexpulsion gap device, said fuse and said device each being provided atits upper end with a terminal having an attachment hook, and unitarymounting structure for said fuse and said device, said mountingstructure including a Z-shape bracket member having one vertical legadapted for attachment to a pole, an insulator secured at one end to asecond vertical leg of said bracket member and supported thereby in ahorizontally projecting posture, an angle iron secured at itsmid-portion to the other end of said insulator and extendinghorizontally in opposite directions therefrom, a metal stirrup securedto and dependin from one end of said angle iron and having a horizontalbar at its lower end for detachably receiving the hook of said fuse fordependingly supporting said fuse, a terminal connector secured to saidstirrup for effecting electrical connection with the upper terminal ofsaid fuse, a second insulator secured to said angle iron and dependingtherefrom at a point remote from said stirrup, a metal strip secured tothe lower end of said second insulator and extending upwardly to form aspark-gap with one end of said angle iron, a second metal stirrupsecured to and depending from the lower end of said second insulator andhaving a horizontal bar portion at its lower end for receiving the hookof said expulsion gap device for dependingly supporting said device, anda plate secured to the lower end of said second insulator and extendingdownwardly therefrom adjacent said second stirrup, said plate serving toprevent said expulsion gap device being positioned on the wrong side ofsaid second stirrup.

LEON A. PHILLIPS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,137,270 Crump Nov. 22, 19382,169,104 Lincks Aug. 8, 1939 2,170,337 Pittman et a1. Aug. 22, 19392,171,179 Johnson Aug, 29, 1939 2,272,370 Fox Feb. 10, 1942 2,294,833Cooley Sept 1, 1942 1,409,927 Christensen Mar. 21, 1922 1,759,253Gerhardt May 20, 1930 2,049,552 Walsh Aug. 4, 1936

